全文获取类型
收费全文 | 788篇 |
免费 | 26篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 33篇 |
综合类 | 1篇 |
化学工业 | 316篇 |
金属工艺 | 20篇 |
机械仪表 | 10篇 |
建筑科学 | 27篇 |
能源动力 | 42篇 |
轻工业 | 66篇 |
水利工程 | 1篇 |
无线电 | 25篇 |
一般工业技术 | 158篇 |
冶金工业 | 25篇 |
原子能技术 | 18篇 |
自动化技术 | 74篇 |
出版年
2023年 | 8篇 |
2022年 | 8篇 |
2021年 | 14篇 |
2020年 | 13篇 |
2019年 | 16篇 |
2018年 | 11篇 |
2017年 | 15篇 |
2016年 | 28篇 |
2015年 | 7篇 |
2014年 | 17篇 |
2013年 | 43篇 |
2012年 | 30篇 |
2011年 | 54篇 |
2010年 | 32篇 |
2009年 | 43篇 |
2008年 | 42篇 |
2007年 | 36篇 |
2006年 | 40篇 |
2005年 | 27篇 |
2004年 | 25篇 |
2003年 | 32篇 |
2002年 | 26篇 |
2001年 | 12篇 |
2000年 | 21篇 |
1999年 | 19篇 |
1998年 | 13篇 |
1997年 | 14篇 |
1996年 | 14篇 |
1995年 | 17篇 |
1994年 | 14篇 |
1993年 | 7篇 |
1992年 | 9篇 |
1991年 | 7篇 |
1990年 | 9篇 |
1989年 | 8篇 |
1988年 | 11篇 |
1987年 | 11篇 |
1986年 | 10篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1983年 | 5篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 10篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 2篇 |
排序方式: 共有816条查询结果,搜索用时 265 毫秒
81.
Johann Kalchman Shingo Fujioka Seok Chung Yamato Kikkawa Toshihiro Mitaka Roger D. Kamm Kazuo Tanishita Ryo Sudo 《Microfluidics and nanofluidics》2013,14(6):969-981
Most anti-cancer drug screening assays are currently performed in two dimensions, on flat, rigid surfaces. However, there are increasing indications that three-dimensional (3D) platforms provide a more realistic setting to investigate accurate morphology, growth, and sensitivity of tumor cells to chemical factors. Moreover, interstitial flow plays a pivotal role in tumor growth. Here, we present a microfluidic 3D platform to investigate behaviors of tumor cells in flow conditions with anti-migratory compounds. Our results show that interstitial flow and its direction have significant impact on migration and growth of hepatocellular carcinoma cell lines such as HepG2 and HLE. In particular, HepG2/HLE cells tend to migrate against interstitial flow, and their growth increases in interstitial flow conditions regardless of the flow direction. Furthermore, this migratory activity of HepG2 cells is enhanced when they are co-cultured with human umbilical vein endothelial cells. We also found that migration activity of HepG2 cells attenuates under hypoxic conditions. In addition, the effect of Artemisinin, an anti-migratory compound, on HepG2 cells was quantitatively analyzed. The microfluidic 3D platform described here is useful to investigate more accurately the effect of anti-migratory drugs on tumor cells and the critical influence of interstitial flow than 2D culture models. 相似文献
82.
Linhua Liu Toshihiro Isobe Kiyoshi Okada Akira Nakajima 《Materials Research Bulletin》2011,46(2):175-184
The respective influences of calcination, drying methods, and washing conditions on the morphologies, surface properties, and photocatalytic activities of TiO2 powders prepared from acid treatments of BaTiO3 were investigated. Rutile powder was obtained using the treatment under strong acid conditions. It possesses a bundle-like shape and comprises rutile nanorods. After calcination, characteristic voids were observed in the particles. Anatase powder was obtained by adjusting pH values of a BaTiO3 suspension to 2.5-3. Drying at 110 °C engendered the formation of spheroidal anatase, although freeze-dried anatase particles assembled into a flake-like shape. The freeze-dried samples show lower crystallinity. With grafting Cu ions, rutile exhibited better photocatalytic performance for the decomposition of gaseous 2-propanol (IPA) under visible light, although it did not work effectively for anatase. 相似文献
83.
Takuya Noguchi Toshihiro Shimada Takashi Chiba Masao Terada Tetsuya Hasegawa 《Diamond and Related Materials》2010,19(2-3):107-109
We have carried out very high temperature heat treatment at 1400–2700 °C of about 10 nm-thick amorphous carbon thin films deposited on refractory substrates MgO, Al2O3, and yttria-stabilized zirconia (YSZ) using pulsed laser deposition techniques. After the annealing, a few nanometer scale sp2 crystallization of the films and a large corrugation with a height of more than 1 μm were observed by Raman spectroscopy analysis and optical/atomic force microscopes, respectively. The corrugation is probably caused by the formation of gases at the film/substrate interface during the heat treatment. 相似文献
84.
85.
Toshihiro Isobe Yoshikazu Kameshima Akira Nakajima Kiyoshi Okada Yuji Hotta 《Journal of Porous Materials》2006,13(3):269-273
The effect of additives on paste rheology was investigated for preparation of porous ceramics with unidirectionally aligned
cylindrical pores. Ammonium poly-carboxylic acid (APA) used as a dispersant and it was adsorbed on alumina powder surface.
The adsorption isotherm of APA was fitted by Langmuir equation. The saturated monolayer adsorption was 5.9 mg/g. The apparent
viscosity became a minimum at 0.8 mass % of APA corresponding to 71.2 mPa⋅s. This APA amount of 5.6 mg/g, is in good agreement
with the observed APA amount. Since the nylon 66 fibers (0–35 vol. %) mixed with the alumina powder have a strong interaction
with each other, they became twisted and agglomerated. This agglomeration increased with increasing fiber content but decreased
by adding oleic acid. The pastes with added oleic acid were capable of being extruded at higher pressure. The obtained porous
alumina ceramics showed highly oriented cylindrical pores parallel to the extrusion direction. The pore orientation was higher
in the oleic acid added pastes than those without oleic acid. The added nylon 66 fibers are mostly converted to pores while
maintaining the original shape after sintering. The pore size distribution of the obtained porous ceramics measured by mercury
porosimetry method showed a peak at about 4 μm which is apparently smaller than that observed in the SEM photographs and the
obtained result is considered to be corresponding to the necks formed by fiber contacts. 相似文献
86.
87.
The microstructure of spray-dried model granules, comprising silica microspheres and poly (vinylalcohol), was observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) with an ultramicrotome technique. Disintegration of granules was characterized by a shear method for granular beds, and by a compression test for single granules. The internal structure changed significantly with the pH of the slurry from which the granules were spray-dried. Granules from pH 7 slurry showed the smallest apparent density, and were disintegrated under the smallest applied load. By analysing the relationship between microstructure, apparent density and flow behaviour of the slurries, it was possible to obtain a guideline for preparation of appropriate granules with controlled microstructure and strength. 相似文献
88.
Muneo Hori Toshihiro Kameda Kenji Oguni 《Mechanics of materials : an international journal》1995,21(4):313-323
To explore a possible mechanism of deep earthquakes, this paper analyzes the unstable propagation of a stress-induced phase transition which is initiated in a homogeneous stress field. This Stephen problem is formulated as an initial-value problem for the phase boundary, and the driving force of the boundary is computed by using the solution of the boundary-value problem for a partially transformed material. The propagation of the phase transition under uniform pressure is numerically simulated. It is shown that (1) under lower pressure, the transition is terminated at a certain size, but it can propagate unstably when an initially transformed region is sufficiently large; and (2) when the pressure attains a critical value, the propagation becomes unstable, and goes in a particular direction depending on the initial shape. These results confirm the possibility of the unstable propagation of phase transition, and provide a theoretical basis for the hypothesis that the phase transition of a mantle material can trigger a deep earthquake. 相似文献
89.
Toshihiro Ohtani 《Metallurgical and Materials Transactions A》2005,36(11):2967-2977
We studied the microstructure evolution of an austenitic stainless steel, Type 316L, subjected to tensile creep at 973 K through
the monitoring of shear-wave attenuation and velocity using electromagnetic acoustic resonance (EMAR). Contactless transduction
based on the Lorentz force mechanism is the key to establishing a monitor for microstructural change in the bulk of metals
with high sensitivity. In the short interval, 60 to 70 pct of the creep life, attenuation experiences a peak, independent
of the applied stress. A drastic change in dislocation mobility and rearrangement interrupted this novel phenomenon, as is
supported by observations using a scanning electron microscope (SEM) and a transmission electron microscope (TEM). The EMAR
exhibited the potential for the assessment of damage advance and the prediction of the remaining creep life of metals. 相似文献
90.
Yoshifumi Ikoma Kazunori Hayano Kaveh Edalati Katsuhiko Saito Qixin Guo Zenji Horita Toshihiro Aoki David J. Smith 《Journal of Materials Science》2014,49(19):6565-6569
This paper describes fabrication of Si nanograins through allotropic phase transformation by concurrent application of high pressure and intense straining using high-pressure torsion (HPT). Single-crystalline Si(100) wafers were processed by HPT under a pressure of 24 GPa at room temperature. X-ray diffraction and Raman analysis revealed that the HPT-processed samples were composed of metastable Si-III and Si-XII phases and amorphous phases in addition to the original diamond-cubic Si-I phase. It was found that nanograins formed because the Si-I diamond phase had transformed to high-pressure phases (Si-II, Si-XI, and Si-V) having metallic nature, and it then became easier to generate a high density of dislocations to form grain boundaries. The high-pressure phases were further transformed to the Si-XII and Si-III phases via the Si-II phase upon unloading and they existed as metastable phases at ambient pressure. Subsequent annealing at 873 K gave rise to reverse transformation to Si-I but with nanograin sizes. Although no appreciable photoluminescence (PL) peak was observed from the HPT-processed sample, a broad PL peak centered around 600 nm was detected from the annealed sample due to quantum confinement in the Si-I nanograins. 相似文献